Microsoft 365 Mass Outage Lasts Over 6 Hours, Outlook, Teams and Other Services Still Unrestored

on November 13, Microsoft 365 services experienced a major outage starting around 1:54 AM Beijing Time today. Initially, it manifested as users in the Americas being unable to access Exchange Online mailboxes, but Microsoft later confirmed that users in any global region could be affected.

According to Microsoft's service health page, affected services include Outlook.com, OneDrive, OneNote, To Do, Teams, and web-based Microsoft 365. Other Microsoft 365 services may also experience issues. As of press time, the outage has lasted over six hours, with the status still listed as "Degraded Service".

Microsoft stated that the outage was not caused by a traffic spike, but rather by a large number of servers unexpectedly becoming unresponsive, which overloaded the remaining infrastructure. An overload on a core process on the affected servers resulted in capacity loss. Microsoft has paused all deployments, restarted the affected servers, and rerouted traffic to alternative paths.

In its latest update, Microsoft noted that previously recovered servers may become unresponsive again once traffic resumes. The company is currently analyzing diagnostic data to identify the root cause, while also restricting traffic types allowed to access the impacted infrastructure in certain regions, and rebuilding some servers using legacy configurations to verify effectiveness. Microsoft expects to release the next update before 12:30 PM Beijing Time.